The present invention relates to hardshell gelatin capsules prepared by the addition of mixed solution of diacetylated monoglycerides, sodium lauryl sulfate and colloidal silicon dioxide during the gelatin film formulation in order to reduce the static electricity and to enhance the lubrication of film, with maintaining the constant film distribution in capsule and its preparation method thereof.
Hardshell gelatin capsule has been conventionally manufactured by following processes; i) dipping, molding and drying gelatin film according to the mold pin dipping method in the capsule manufacturing machine, ii) stripping off the gelatin film from mold pin and cutting off, iii) joining the film of cap and the film of body to be one set of capsule at the Joiner Block made by metal substance, and iv) finally, ejecting out prepared gelatin capsule by Ejector Rod.
In the course of joining the film of cap and the film of body, static electricity sometimes generates and induces low film flexibility, which causes the bad joint or telescope, one of fatal badness in capsule manufacturing industry. Further, the bad joint causes the separation of cap and body during the transportation and the badness in imprinting process as well as the badness in filling the capsule.
To solve the above problems, it has been conventionally used to add glycerine or sorbitol to the gelatin solution to maintain the flexibility of capsule film. However, such plasticizer induces the delay of drying at the drying step after molding step in the capsule manufacturing machine. Further, it also induces some drawbacks such as deformation and contraction of the film of cap or body at the time of long term storage. Therefore, those plasticizers increase the unstability of gelatin capsules with time.
In Japanese laying open patent No. 6-157916, it is disclosed that 3˜10 wt % of glycerine fatty acid ester is added to the gelatin solution during the manufacturing the gelatin capsule film. Further, as an example of glycerine fatty acid ester, diacetylated monoglycerides was disclosed. However, the purpose for using glycerine fatty acid ester in gelatin solution is to maintain the elasticity of gelatin film at the time of filling hygroscopic drug as internal ingredient, because such preparation protects the absorption of moisture from the gelatin capsule film to the hygroscopic internal drug. Further, such preparation protects the leakage of internal drug at the time of external impact to the capsule.
To solve the above problems, the inventors design the reformation of gelatin film formulation in order to reduce the static electricity and to enhance the lubrication of film, with maintaining the constant film distribution in capsule. For this purpose, diacetylated monoglyceride is employed together with sodium lauryl sulfate which emulsifies the mixed gelatin solution by reducing the surface tension between water phase and oil phase.
On the other hand, colloidal silicon dioxide is also employed in order to maintain the constant film distribution in capsule, by reducing the entasis formulation caused by flow of gelatin by using diacetylated monoglycerides.
Such ingredients, diacetylated monoglycerides and sodium lauryl sulfate are recorded in NF. In this reference, diacetylated monoglycerides is described in various usage, for example, anti-dusting agent, deforming agent, lubricant, stabilizer, plasticizer or release agent. However, in this invention, diacetylated monoglycerides is used as an agent for reducing static electricity.
Further, colloidal silicon dioxide also has a role of caking agent to avoid the flow of gelatin from mold pin in order to maintain the constant film distribution in capsule.